text: import perf
  from perf import _cli as cli
  from perf.tests import unittest
  
  
  class CLITests(unittest.TestCase):
      def test_format_result(self):
          run = perf.Run([1.0, 1.5, 2.0],
                         warmups=[(1, 3.0)],
                         metadata={'name': 'mybench'},
                         collect_metadata=False)
          bench = perf.Benchmark([run])
          self.assertEqual(cli.format_result_value(bench),
                           '1.50 sec +- 0.50 sec')
          self.assertEqual(cli.format_result(bench),
                           'Mean +- std dev: 1.50 sec +- 0.50 sec')
  
      def test_format_result_calibration(self):
          run = perf.Run([], warmups=[(100, 1.0)],
                         metadata={'name': 'bench', 'loops': 100},
                         collect_metadata=False)
          bench = perf.Benchmark([run])
          self.assertEqual(cli.format_result_value(bench),
                           '<calibration: 100 loops>')
          self.assertEqual(cli.format_result(bench),
                           'Calibration: 100 loops')
          self.assertRaises(ValueError, bench.median)
  
  
  if __name__ == "__main__":
      unittest.main()
  